System and method for battery charging
First Claim
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1. A charging circuit for charging a battery, comprising:
- a pulse generator for generating a plurality of pulses to control an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET);
a controller coupled to said pulse generator for controlling a pulse density of said plurality of pulses according to a status of said battery;
a charge pump coupled to said pulse generator for receiving said plurality of pulses and for generating a driving signal; and
a resistor coupled to a gate of said NMOSFET, wherein said resistor and a capacitance of said gate of said NMOSFET form a low pass filter, wherein said driving signal is filtered by said low pass filter to control a gate voltage of said NMOSFET, wherein a variation of a gate-source voltage of said NMOSFET is proportional to said pulse density, and wherein a variation of a charging current flowing through said NMOSFET to said battery is proportional to said pulse density.
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Abstract
A charging circuit includes a pulse generator and a controller coupled to the pulse generator. The pulse generator is used to generate a plurality of pulses to control a charging switch. The controller is used to control a pulse density of the plurality of pulses. A charging current flowing through the charging switch can be adjusted according to the pulse density.
6 Citations
20 Claims
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1. A charging circuit for charging a battery, comprising:
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a pulse generator for generating a plurality of pulses to control an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET); a controller coupled to said pulse generator for controlling a pulse density of said plurality of pulses according to a status of said battery; a charge pump coupled to said pulse generator for receiving said plurality of pulses and for generating a driving signal; and a resistor coupled to a gate of said NMOSFET, wherein said resistor and a capacitance of said gate of said NMOSFET form a low pass filter, wherein said driving signal is filtered by said low pass filter to control a gate voltage of said NMOSFET, wherein a variation of a gate-source voltage of said NMOSFET is proportional to said pulse density, and wherein a variation of a charging current flowing through said NMOSFET to said battery is proportional to said pulse density. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for charging a battery, comprising:
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generating a plurality of pulses to control an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET); controlling a pulse density of said plurality of pulses according to a status of said battery; generating a driving signal based on said pulse density of said plurality of pulses; filtering said driving signal by a low pass filter formed by a resistor coupled to a gate of said NMOSFET and a capacitance of said gate of said NMOSFET; controlling a gate voltage of said NMOSFET by said driving signal, wherein a variation of a gate-source voltage of said NMOSFET is proportional to said pulse density, and wherein a variation of a charging current flowing through said NMOSFET to said battery is proportional to said pulse density. - View Dependent Claims (14, 15, 16, 17)
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18. An electronic device comprising:
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a charger for charging a battery; a charging circuit coupled to said battery and said charger for controlling a charging current from said charger to said battery, comprising; a pulse generator for generating a plurality of pulses to control an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) coupled between said charger and said battery; a controller coupled to said pulse generator for controlling a pulse density of said plurality of pulses according to a status of said battery; a charge pump coupled to said pulse generator for receiving said plurality of pulses and for generating a driving signal; and a resistor coupled to a gate of said NMOSFET, wherein said resistor and a capacitance of said gate of said NMOSFET form a low pass filter, wherein said driving signal is filtered by said low pass filter to control a gate voltage of said NMOSFET, wherein a variation of a gate-source voltage of said NMOSFET is proportional to said pulse density, and wherein a variation of said charging current flowing through said NMOSFET to said battery is proportional to said pulse density. - View Dependent Claims (19, 20)
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Specification